Treatment of distillates with hypochlorite solution



Oct. 18, 1955 H. w. EARHART TREATMENT OF DISTILLATES WITH HYPOCHLORITE SOLUTION Filed OCT.. 23, 1952 INVENTOR. Harold W. Earh arf,

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n" muuu United States Patent O TREATMENT OF DISTILLATES WITH HYPOCHLORITE SOLUTION Harold W. Earhart, Baytown, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application October 23, 1952, Serial No. 316,386

7 Claims. (Cl. 196--29) The present invention is directed to a method for treating a hydrocarbon distillate. More particularly, the invention is directed to treating a petroleum distillate boiling below 750 F. which contains acidic chlorinated compounds. ln its more specific aspects, the invention is directed to a method for treating a petroleum distillate with an alkaline hypochlorite solution following which the alkaline hypochlorite treated distillate is treated to convert acidic chlorinated compounds to innocuous compounds.

The present invention may be described briefly as involving treating a hypochlorite treated distillate boiling below 750 F. and containing acidic chlorinated compounds With a solution consisting of water, alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of aromatic mercaptides and aliphatic mercaptides having no more than 4 carbon atoms in the molecule.

The invention also includes the treatment of a hydrocarbon distillate boiling below 750 F. with an alkaline hypochlorite solution following which the alkaline hypochlorite solution is separated from the hydrocarbon distillate and the hypochlorite treated hydrocarbon distillate is then washed or contacted with an aqueous solution of an alkali metal hydroxide and an alkali metal mercaptide of the type illustrated for a sufficient length of time to convert acidic chlorinated compounds in the hydrocarbon distillate to innocuous compounds and to form in said distillate disultides and in the solution of alkali metal hydroxide and alkali metal mercaptide an amount of alkali metal chloride and then employing the latter solution to contact additional quantities of the hypochlorite treated distillate containing acidic chlorinated compounds.

The mercaptans employed to make up the solution consisting of water, alkali metal hydroxide and alkali metal mercaptide may be an aliphatic mercaptan having no more than 4 carbon atoms in the molecule, such as methyl mercaptan, ethyl mercaptan, iso and normal propyl mercaptan and the butyl mercaptans, such as tertiary, primary and secondary butyl mercaptans or an aromatic mercaptan such as benzene thiol, a thiocresol such as ortho, meta, or para thiocresol, 2-phenyl l-ethane thiol, 4 ethyl benzene thiol, methyl benzyl mercaptan, Z-naphthlene thiol, and 4-phenyl-l-benzene thiol.

The solution of alkali metal mercaptide may suitably be formed by extracting mercaptans from the feed stock prior to treatment with the hypochlorite solution provided hydrogen sulfide is removed from the feed stock prior to contact of the feed stock with an alkali metal hydroxide solution to form the alkali metal mercaptide. Removal of hydrogen sulfide may be accomplished by washing a feed stock containing hydrogen sulfide with a 5 B. aqueous sodium hydroxide solution or by distillation to remove hydrogen sulfide and light fractions. Preferably, hydrogen sulfide is removed with a sodium hydroxide solution.

After removal of hydrogen sulde and/ or other acidic material reactive with the hypohlorite solution the hydrogen sulfide-free feed stock is then contacted with a stronger aqueous sodium hydroxide solution, say one of about ICC B., to extract therefrom at least a portion of the mercaptans, particularly the low molecular weight mercaptans such as methyl, ethyl, propyl, and butyl mercaptans and also the aromatic mercaptans present. The higher mercaptans such as the pentyl and hexyl mercaptans may also be removed. Removal of such mercaptans is desirable since consumption of chlorine in the subsequent hypochlorite treating step is thereby reduced. The sodium mercaptide solution thus formed may then be used to treat the hypochlorite sweetened oil.

The alkali metal mercaptide solution may also be prepared by adding a mercaptan of the types illustrated to an equeous solution of alkali metal hydroxide. v

When the alkali metal mercaptide solution is formed by extracting mercaptans from the feed stock, the solution may contain besides the alkali metal mercaptides, alkali metal phenolates, naphthenates, alkali metal salts of other carboxylic acids and unreacted alkali metal hydroxide and Water. The presence of the salts of carboxylic acids and/ or phenolates and naphthenates is not deleterious and does not affect the efficacy of thev alkali metal mercaptide treat. Y

The hydrocarbon distillate employed as a feed stock in the present invention may be any hydrocarbon distillate such as a petroleum distillate boiling below 750 F. which may contain hydrogen sulfide, mercaptans and other acidic materials. Thus the feed stock to the present invention may be a liquefied normally gaseous hydrocarbon fraction, such as butane, or it may be a gasoline fraction boiling in the range from about to about 450 F. or it may be a kerosene fraction boiling in the range from about ,450 F. to about 650 F. or, as stated hereinbefore, the petroleum distillate may boil up to 75 0 F.

The solution employed to remove the acidity of the side reaction products which are present in the hypochlorite treated oil will consist of water, alkali metal hydroxide and alkali metal mercaptides. The alkali metal hydroxide may be present lin an amount in the range from 1.0% by weight to 15% by weight and the alkali metal mercaptide may be present in an amount in the range from 50.0 to 600.0 mgs. (mgs. of RSNa per ml.) with the remainder being water. Although it is preferred to use sodium hydroxide and hence a sodium mercaptide, it is within the purview of my invention to employ the other alkali metal compounds, such as those of lithium and potassium. Sodium hydroxide is preferred because of its economic availability.

In treating a hypochlorite treated oil with the treating reagent consisting essentially of water, alkali metal hydroxide and alkali metal mercaptide, an amount of treating reagent in the range from about 5% to about 30% by volume should be used with good results being obtained with about 20% by volume based on the hypochlorite treated oil.

The present invention will be conducted ordinarily at temperatures ranging from about 60 F. up to about F. with temperatures Within the range from about 75 F. to about 100 F. preferred. However, higher temperatures up to about 250 F. may be used under some conditions. When higher temperatures are used it may be desirable to superimpose pressure on the treating equipment to maintain the liquid phase.

The invention Will be further illustrated by reference to the drawing in which the single gure is a flow diagram of a preferred mode.

Referring now to the drawing, numeral 11 designates a line through which is admitted a feed stock such as a sour hydrocarbon fraction as one in the gasoline boiling range containing, for example, mercaptans and hydrogen sulfide. The feed stock in line 11 has admixed with it by way of line 12 a solution of sodium hydroxide having, for example, a B. gravity of about 5. The amount v after.

of this caustic solution injected will`be about by volume based on the feed oil.V The feed oil and the sodium hydroxide solution are intimately admixed in an incorporator or mixing device 13 which is shown as a bafiie plate mixer but which may be any suitable mixing device, such as jets, yagitators, contacting towers, centrifugal pumps and the like. Any contacting device which will give intimate admixture between the feed and the caustic may be suitable. Y

The admixture of feed and caustic solution is then discharged from incorporatorr13 by line 14 into a first prewash settling zone 15 which may be any desirable form of settling tank. In pre-wash settling tank 15 thecaustic pre-washed oil has substantially all of its hydrogen sulfide removed by the caustic and is discharged by line 16 Vfor further treatment as will be described hereafter. The

caustic solution is discharged from settling zone 15 by line 17 and preferably is recycled to line 12 by connecting line 18v containing a pump 19 and controlled by a valve 20.

From time to time it may be desirable to discard theV caustic solution in part from line 17 Vand Ythis may b e done by opening valve 20. When an amount of the caustic solution is discarded by opening valve 17 in line 17 a Vsimilar amount of fresh caustic solutionwill be introduced into thesystem by opening valve 21 in line 12.

The washed feedsubstantially free of hydrogen sulfide Vbut still sour to the doctor test is withdrawn by line 16 and is admixed inline 22 with a caustic solution having a Be. gravity of about 15 introduced by line 22a from a source which will be described in more detail heretlingvzone 25 which isY of sufficient capacity to provide Va suitable residence time for separation of the caustic solution from the caustic treated oil.

The first caustic washing operation with 5 B. sodium hydroxide solution removes hydrogen sulfide from the f eed oil and the second caustic washing operation removes` mercaptans, and also phenols, naphthenic and other carboxylic acids as well as other acidic bodies, Vif present in the feed. The solution resulting from the second caustic washing operation is free of sodiumV sulfide but does contain sodium mercaptide and may also'contain `sodium salts of the acidic materials Ymentioned and may be used as will be described further hereinafter. Y

The caustic solution from prefwash settling zone 25 is dischargedv therefrom byY line 26 and'mayrbe recycled by branch line 27 containing pump 28 and controlled by valve. 29 Vto line V22a for admixture with the oil in line 22 for treating same as has beenrdescribed. Fromtimeto time it mayl be necessary 'to add fresh Ycaustic solution such as a 15 B. sodium hydroxide solution to the oil being treated in line 22. This may be done by opening the valve 30 in line 22a. The caustic solution withdrawn from settling zone 25 in lineY 26 may be discharged in part from the system ,by opening valve 31 in line 26 but preferably is employed in a later stage of the process by discharging same intoV line 32 controlled by valve 33 and containing pump 34. The subsequent employment of this caustic stream will be'describe'd in 'more detail herein- ,n The pre-washed oil is removed from zonel25 by line 35 and has added thereto a hypochlorite solution which is introduced by line 36 from a source which willV be described in more detail hereinafter. This hypochlorite solution may bea sodium hypochlorite solution `or it may Y suitably be a calcium hypochlorite solution or any hypo- In incorporator 37 intimate contact is effected between the hypochlorite solution and the caustic washed feed and the contacted mixture is then discharged by line 38 into a hypochlorite settling zone 39 which is` of suiiicient capacity to provide a suitable residence time for separation of the hypochlorite solution from the hypochlorite treated oil. Y Y

The contacting of the oil` in line and incorporator 37 with the hypochlorite solution results in the formation in the oil of acidic chlorinatedacompounds of atyp'eV such as the sulfonyl and sulfenyl as well as the sulfinyl chlorides. TheseY compounds are deleterious in motor fuel in that they affect the product quality of the finished Y motor hiel, such as the breakdown time or induction period (ASTM 525-46). Inaccordance with my invention, these acidic chlorinated compounds are converted to innocuous compounds as will be described further.

The hypochlorite solution separated from the treated feed in settling zone 39 is withdrawn therefrom by line 40 Y and routed by line 41 into a hypochlorite generation zonev 42. The hypochlorite solution owing through line 4l may have added to it from time to time or continuously, if desired, an amount of sodium hydroxide which is accom-k plished by line 43 containing valve .42 connected to a source of caustic solution, not shown. Hypochlorite generation 'zone 42 is provided with a line 44'controlled by valve 45 connecting to a source of chlorine to allow formation in zone 42 of sodium hypochlorite solution which is withdrawn therefrom by line 36, as has Ybeen described, containing pump 46.

The hypochlorite treated oil is Aremoved from settling zone 39vby line 47; and there is admixed inline 47 with` the hypochlorite treated oil a solution originally consisting essentially of water, sodium mercaptide and sodium yhydroxide. The sodium mercaptide suitably may be sodium` methyl mercaptide. This solution is introduced into line 47 by line 48 as will be described hereinafter. The admixture of sodium mercaptide solution and hypochlorite treated oilfiows into an incorporating device 49 which Y is shown as a baffle-type incorporator butV mayk be an incorporating device, such as incorporators 23, 13,'or 37, as has been described. The sodium mercaptide solution and the hypochlorite treated oil are intimately admixed in incorporator 49 and are then discharged by line 50 into a sodium mercaptide settling zone 51 which is simi-k lar to settling zones 39, 25, and 15. After separation by gravity of the sodium mercaptide solutionjin zone 51, the solution is withdrawn fromy zone 51 by.line.52 and preferably is recycled to Vliner48 by branch line 53 .containing pump 54 and controlled by valve 55. The recycled solution contains as a result of the contacting operation sodium chloride and other reaction products resulting sulfide. such as sodium sulfonate and sodium thiol sulfonate, do

not deleteriously affect the conversion of the acidic Vcom-l pounds supra. l

From Vtime to time it may be necessary to withdraw aportion of sodium'mercaptide solution and this may be done conveniently by opening valve 56 in line 52. When the sodium mercaptan solution is withdrawn from line 52 an amount of make-'up solution equivalent to that withdrawn may be introduced by opening valve 57 in lineS. A

In lieu of extraneously prepared make-up solution, I may, and preferably do, employ part ofthe solutionwithdrawn from settler 25 byway of line 32. This solution consists essentially of water, sodium hydroxide, and sodium mercaptides fromthe group consisting 4of sodium alkyl mercaptides having no more than 6 carbon atoms per molecule, and sodium aryl mercaptides, and is free of sodium sulfide. i 'Y When sodium methyl mercaptide or sodium ethyl mercaptide solution is used, there may be withdraw/171l from zone 51 by line 58 a treated oil which may be routedk to storage by opening valve 59. However, when other mercaptides of the types illustrated are employed in the treating solution it may be necessary to treat the treated oil further to remove mercaptans, such as propyl or butyl mercaptans, which may be in the treated oil phase by virtue of extraction from the sodium mercaptide solution through a mechanism which may involve hydrolysis. Under these conditions, I, therefore, admix with the oil in line 58 a quantity of sodium hydroxide solution, for example, which is introduced by line 60. The treated oil and sodium hydroxide solution then ow by way of branch line 61 controlled by valve 62 into an incorporating device 63 which may be of the baffle type and is similar to incorporator 49, 37, 23, and 13. The caustic solution and the treated oil are intimately admixed in incorporator 63 and are withdrawn therefrom by way of line 64 and discharged into an after-wash settling zone 65 which is like settling zones 51, 39, 25, and 15. Treated oil may then be withdrawn from the system for storage and further use by line 66 controlled by valve 67. The used sodium hydroxide solution is withdrawn from zone 65 by line 68 and may be recycled, in part, by branch line 69 containing pump 70 to line 60 on opening valve 71. The solution in line 69 may also be discharged in part into line 32 byv opening valve 72. Line 32 discharges into line 48.

It is desirable and preferable in this latter described mode that at least a portion of the solution withdrawn from zone 65 by line 68 be employed as the source of the sodium mercaptide solution along with that from line 32. Since all of the caustic solution withdrawn by line 68 is not' recycled to line 60, I, therefore, introduce an amount of make-up sodium hydroxide solution by opening valve 73 in line 74. Also I contemplate that it may be desirable from time to time to discard a portion of the sodium hydroxide solution from the system by opening valve 75 in line 68.

As a modification of my invention, I may by-pass completely the treating system including incorporator 13 and first pre-wash settling zone 15. Under these conditions valve 76 in line 14 is closed and valve 77 in line 16 is also closed, and valve 78 in line 22 is opened, allowing the feed stock to be introduced by line 22 into incorporator 23 for operation as has been described. Under these conditions the caustic solution introduced into line 22 by line 22a will serve to remove not only hydrogen sulde but also the mercaptans having 6 and less carbon atoms in the molecule as well as the phenolic, naphthenic, and other carboxylic acid bodies. should not be recycled from line 26 to line 32 for use in line 48 since this solution would then contain sodium suliide which is not as eective as the sodium mercaptide This caustic solution introduced into the system by line 48 on opening valve 57. In operation in such a manner with the sodium mercaptide solution being introduced by line 48, I may also eliminate from the operation the treating facilities including the incorporator 63, settling zone 65, and the attendant lines, provided the solution introduced by opening valve 57 contains no mercaptide other than methyl and ethyl.

It may be seen from the foregoing description taken with the drawing that I have provided a process for converting the acidity of chlorinated compounds present in oils which have been treated with hypochlorite and this treatment has converted the acidic chlorinated compounds which are of the type mentioned before into innocuous compounds which do not deleteriously aiect the product quality of the gasoline or the oil being treated for use as a motor fuel.

The invention will be further illustrated by a number of runs wherein the practice of the present invention is compared to washing the hypochlorite sweetened oil with other reagents, for example, aqueous sodium sulfide solution and an alkaline solution obtained in a petroleum refinery resulting from treating an oil containing mercaptans, HzS, phenolic bodies, naphthenic acids and the vlike With a caustic solution.

In the rst instance a heptane fraction was divided into two portions and one portion had added to it a suflicient amount of normal amyl mercaptan to provide a stock having a copper number of 100, while the second portion had added to it an amount of tertiary amyl mercaptan suficient to provide a stock also having a copper number of 100.

The heptane fraction containing the normal amyl mercaptan was treated with sodium hypochlorite solution and the sodium hypochlorite treated heptane fraction was then divided into three portions. One portion of the hypochlorite treated heptane was inspected as is. The second portion was treated with 20% by volume based on the hypochlorite treated oil of an aqueous sodium sulfide solution containing 148 grams of sodium sulfide per liter. The third portion was treated with a solution containing 80 grams per liter of free sodium hydroxide and also sodium ethyl mercaptide to the extent of 600 mgs. of mercaptide sulfur per ml.

The heptane fraction to which tertiary amyl mercaptan was added was treated in a manner similar to that of the above mentioned fraction in that one hypochlorite sweetened fraction was inspected as is, one was washed with sodium sullide solution, and one was washed with sodium ethyl mercaptide solution. In all of these operations the hypochlorite treated oils were contacted with the several solutions for one minute contacting time.

The results of these runs are given in Table I.

Table I Sweetening Method Hypoehlorite Steek Swppfpn ed Heptane Containing N-Amyl Mereaptan Heptane Containing T-Amyl Mercaptan Type of Afterwash (20 Vol. Percent) 1 None Sodium Sul- Sodium Ethyl Neuem. Sodium Sul- Sodium Ethyl fide. Mereaptide. de. Mercaptide. Inspection of Treating Solution:

NazS, g. p. 1 148 None 148 None. Free NaOH, g. p. l 0. S0-- 0 80. Mercaptide Sulfur, mgs./100 ml 600 600. Inspections on Treated Oil:

Wt. Percent Cla 0.0129... 0.000. Acidity, mls. 0f 0.1 N KOH/100 ml 4.0 0.12. Sulfur as Free Sulfur or Polysultide Sulfur 0 0.0.

mgs./100 ml. Corrosion 3 hrs. at 212 F. #4 #4.

1 Reaction time of l min. employed.

in treating the hypochlorite solution. When treating facilities including incorporator 13, feed line 11, and settling zone 15 are eliminated from the system I employ a sodium mercaptide solution such as a sodium aliphatic mercaptide solution or sodium mercaptide solution formed With respect to the inspections employed in these experiments, it may be mentioned that the copper number is numerically the same as the milligrams of mercaptan sulfur present in 100 milliliters of 0:1. The corrosion number is an indication of the amount of free sulfur with an aromatic mercaptan. This solution would be 75 or equivalent material present in the oil. It is deter- Vmined by A. S. T. M. test No. DBD-50T. Briey, the

corrosion test consists of immersing a portion of a copper strip' in a given quantity of sample and heating it at a temperature and for a time characteristic of the treated oils with sodium sulfide solution or alkaline solution containing both sodium sulfide and sodium mercaptide; f

The hypochlorite solution employed in the practice of Stock sweetened materiall being tested. In the present case, the strip was the present invention is preferably sodiumr hypochlorite immersed in normal heptane at its boiling point under but mayV be an alkaline earth hypochlorite such asV calreux conditions for three hours. The discoloration ofV cium hypochlorite; It is contemplated that the other a strip is indicative of the corrosiveness of the sample. alkali metal hypochlorites may be employed such as It is rated by numbers which are determined by comlithium and-potassium hypochlorites or that the hypoparison with standard test strips. A number of zero vchlorite solution may be asolution of an alkaline earth hyindicates no tarnish; 4 is considered slightly corrosive, lpoclilorite such-as magnesium, calcium, and strontium hyand greater than-4 indicates pronounced corrosionV to an pochlorite. v increasing extent. The hypochlorite solution will ordinarily have an avail- '..The data in Table I show that the sodium mercaptide able chlorine content in the range from about 2 grams treated oil is free of sulfur as free sulfur and polysulper liter to about 150 grams per liter;V concentration of Vfide sulfur, whereas the oil which has been hypochlorite about l0 grams per liter gives good results. treated and then washed ywith sodium suliide contains Y The hypochlorite solution when it is sodium hypoconsiderable quantities of free sulfur or polysulfide sulchlorite solution will preferably have an average sodium fur. In short, my invention provides a hypochlorite hydroxide content ranging from about 5 to about 750 treated product'substantiallyVfree of sulfur in these forms. 2,0 Vgrams of sodium hydroxide per-liter. Ordinarily, the This is also reflected in the corrosion test in that my hypochlorite solution employed will contain free sodium invention allows the obtaining of a lower corrosion numhydroxide in the range from about 50 to 100 grams per ber, which vis also an indication of the absence of free liter. It may be stated, however, that the present inor polysulfide sulfur, than is obtainable with the hypovention has mostapplicability to treatment of naphthas chlorite Vtreated oil Whichwas treated with sodium sulwhich have been contacted with hypochlorite solutions tide.` l having a low level Vof causticity since naphthastreated In order toillustrate further the benefits of my invenwith sodium hypochlorite having a small amount of free tion, a comparison was made using a heptane fraction sodium hydroxide are generally more unstable than those which contained tertiary butyl mercaptan in an amount having a high level of free sodium hydroxide. Y Y suicient to provide a copper number of 200 in the hep- 3Q In practicing the present invention, it is desirable to tane. This heptane having a copper number of 200 was maintain the alkalinity of the hypochlorite solution emtreated with a sodium hypochloriteV solution and the ployed in the process at a high level in order to minimize sodium Yhypochlorite treated heptane was divided into consumption of hypochlorite and corrosion of equipment, three portions. One portion-of the hypochlorite treated since in employinghypochlorite solutions having an averheptane was inspected as is and the other two portions age sodium hydroxide content belowl about 90 grams per were treated, respectively, with a sodium normal butyl liter ferrous metal equipment is rapidly attackedk by the mercaptide solution containing sodium hydroxide and hypochlorite. Therefore, it is contemplated that sufwater, and with an'alkaline solution resulting from treatcient sodium hydroxide will be added to the process as ing a mercaptanand hydrogen sulfide-containing oil with described to maintain the causticity at above 90 grams sodiumV hydroxide. Inspections on the solutions used L40 per liter. It is further contemplated that sufficient chloto treat the hypochlorite treated heptane, and inspections v rinewill be addedas make-up to Vreplace that consumed on the heptane after treating withv hypochlorite, hypo- Y or discarded. When employing high caustic content hychlorite and sodium normal butyl mercaptide solution, pochlorite solution Vit is desirable to add sodium hyand Vwith the alkaline solution obtained from the refining droxide and chlorine as make-up and to withdraw a poroperations where the oil, as described, was treated, ar tion of the yhypochlorite solution to prevent build-up of given in Table Il. sodium chloride in the system.

Table ll s Sxveetening Method Hypochlorite N-heptane, Containing Tertiary Butyl Mercaptan Afterwash Used (20 Vol. percent.)

None N-butyl Mercaptide. Reaction Time 1Minute 1 Minute' mgs./100 ml.

Plant .Spent Treating Caustic. 1 Minute.

It will be seen that the alkaline solution obtainedVV from the refining operations contained sodium hydroxide,

sodium sulfide and sodium mercaptide as Well as some phenolic compounds and that the sodium normal butyl mercaptide consisted of sodiumV hydroxide, sodium normal butyl mercaptide and water. It will also be noted that the oil treated in accordance with my invention had a sulfur content as free sulfur or' polysulfide sulfur of zero while that treated with the alkaline caustic solution contained l5 mgs./ 100 ml. of sulfur. Y

From the foregoing results presented in Tables I and II lit* will be seen that my invention gives improved results over that obtained when treatinghypochlorite v In the description taken with the Vdrawing provision is made for discarding sodium mercaptide solution through -line 52 controlled by valve 56. This should be done hydroxide to sodium mercaptide but it is always desirable to leave a suicient amount of caustic in the solution The mercaptide solution should be discardt to provide a solution consisting essentially of water, alkali metal mercaptide and alkali metal hydroxide and reaction products such as sodium sulnate and sodium thiolsulfonate.

By way of explanation it will be desirable to recycle the solution from zone 65 to line 32 by way of line 69 when the solution in zone 65 becomes saturated with sodium mercaptide to the extent that it would no longer extract mercaptans from the oil in line 58.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

l. A method for treating a hypochlorite treated hydrocarbon distillate boiling below 750 F. containingI acidic chlorinated compounds which comprises contacting said distillate with a solution consisting of water, alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of the aromatic mercaptides and aliphatic mercaptides having no more than 4 carbon atoms in the molecule.

2. A method for treating a hypochlorite treated hydrocarbon distillate boiling below 750 F. containing acidic chlorinated compounds which comprises contacting said distillate with a solution consisting of water, alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of aromatic mercaptides and aliphatic mercaptides, having no more than 4 carbon atoms in the molecule for a suicient length of time to convert acidic chlorinated compounds in said hydrocarbon distillate and to form in said distillate disultides and in said solution alkali metal chloride, separating said contacted distillate from said aqueous solution containing alkali metal chloride and employing said separated solution to contact additional quantities of hypo chlorite treated hydrocarbon distillate containing acidic chlorinated compounds.

3. A method for treating a sour hydrocarbon distillate boiling below 750 F. which comprises contacting said distillate with an aqueous hypochlorite solution whereby acidic chlorinated compounds are formed, separating said contacted distillate from said hypochlorite solution, treating said contacted distillate with a solution consisting of water, alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of aromatic mercaptides and aliphatic mercaptides having no more than 4 carbon atoms in the molecule for a sufficient length of time to convert acidic chlorinated compounds in said contacted distillate and to form disuldes in said treated distillate and in said solution alkali metal chloride, separating said treated distillate from said aqueous solution containing alkali metal chloride and employing said separated solution to contact additional quantities of said hypochlorite treated distillate containing acidic chlorinated compounds 4. A method for treating a sour hydrocarbon distillate boiling below 750 F. containing hydrogen sulfide and mercaptans which comprises removing hydrogen sulde from said sour distillate, contacting the hydrogen sulde free sour distillate with an aqueous caustic solution to form an aqueous solution containing alkali metal mercaptides, treating said last-contacted distillate with an aqueous hypochlorite solution, separating said treated distillate from said hypochlorite solution, contacting the treated distillate with a solution consisting of water, alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of the aromatic mercaptides and the aliphatic mercaptides having no more than 4 carbon atoms in the molecule, separating mercaptide solution from said treated distillate, and recovering said hypochlorite treated oil.

5. A method for treating a sour distillate boiling below 750 F. containing hydrogen sulde and aliphatic mercaptans including mercaptans having at least six carbon atoms in the molecule which comprises removing hydrogen sulde and said aliphatic mercaptans having six and less carbon atoms in the molecule from said sour distillate, treating the sour distillate, after removal of hydrogen sulfide and said aliphatic mercaptans, with an aqueous hypochlorite solution, separating the treated distillate from said hypochlorite solution, and contacting the treated distillate with a solution consisting of water alkali metal hydroxide and an alkali metal mercaptide selected from the group consisting of the aromatic mercaptides and the aliphatic mercaptides having no more than four carbon atoms in the molecule.

6. A method for treating a hypochlorite treated hydrocarbon distillate boiling below 750 F. containing acidic chlorinated compounds which comprises contacting said distillate with an aqueous solution consisting of sodium hydroxide, Water, and an alkali metal mercaptide selected from the group consisting of the aromatic mercaptides and the aliphatic mercaptides having no more than four carbon atoms in the molecule.

7. A method for treating a hypochlorite treated hydrocarbon distillate boiling below 750 F. containing acidic chlorinated compounds which comprises contacting said distillate with an aqueous solution consisting of an alkali metal hydroxide, water, and an alkali metal mercaptide selected from the group consisting of methyl mercaptan, ethyl mercaptan, propyl mercaptans, butyl mercaptans, benzene thiol, thiocresols, 2-phenyl l-ethane thiol, m-tolubenzyl mercaptan, 4ethyl benzene thiol, methyl benzyl mercaptan, 2-naphthalene thiol, and 4-phenyl-l-benzene thiol.

References Cited in the file of this patent UNITED STATES PATENTS 2,581,117 Love Ian. 1, 1952 

3. A METHOD FOR TREATING A SOUR HYDROCARBON DISTILLATE BOILING BELOW 750* F. WHICH COMPRISES CONTACTING SAID DISTILLATE WITH AN AQUEOUS HYPOCHLORITE SOLUTION WHEREBY ACIDIC CHLORINATED COMPOUNDS ARE FORMED, SEPARATING SAID CONTACTED DISTILLATE FROM SAID HYPOCHLORITE SOLUTION, TREATING SAID CONTACTED DISTILLATE WITH A SOLUTION CONSISTING OF WATER, ALKALI METAL HYDROXIDE AND AN ALKALI METAL MERCAPIDE SELECTED FROM THE GROUP CONSISTING OF AROMATIC MERCAPTIDES AND ALIPHATIC MERCAPTIDES HAVING NO MORE THAN 4 CARBON ATOMS IN THE MOLECULE FOR A SUFFICIENT LENGTH OF TIME TO CONVERT ACIDIC CHLORINATED COMPOUNDS IN SAID CONTACTED DISTILLATE AND TO FORM DISULFIDES IN SAID TREATED DISTILLATE AND IN SAID SOLUTION ALKALI METAL CHLORIDE, SEPARATING SAID TREATED DISTILLATE FROM SAID AQUEOUS SOLUTION CONTAINING ALKALI METAL CHLORIDE AND EMPLOYING SAID SEPARATED SOLUTION TO CONTACT ADDITIONAL QUANTITIES OF SAID HYPOCHLORITE TREATED DISTILLATE CONTAINING ACIDIC CHLORINATED COMPOUNDS 